The present invention relates generally to machine tools and accessories for use in precision machining operations and, more particularly, to axial and radial tool offset indicators for use in setting up manually or numerically controlled metal cutting machinery.
In present day machining operations using numerical or computer controlled machines, it is necessary to very precisely determine the location of a tool tip or cutting edge with respect to machine coordinates or the surface of a workpiece. By so precisely locating the tool tip or cutting edge, the machines may be programmed to perform extremely accurate cutting, milling and drilling operations.
Tool tip or workpiece locating is performed during the initial setup of the machine or whenever a dull or broken tool must be replaced during operation. To determine the correct offset of a tool tip with respect to the machine coordinates, the workpiece, or a reference indicating device, is approached to just touch the surface thereof and record the tool tip or cutting edge location relative to a reference surface as indicated by the machine readout. Thereafter the machine may be programmed for a complete machining operation taking into account the precise tool offset.
If the tool is already mounted in the holder, the cutting tool or workpiece edge may be damaged during setup if it is inadvertantly driven into the surface of the workpiece or other reference surface. In addition, if the workpiece is already mounted, its surface may be scarred, or if the material of the workpiece is soft enough, the accuracy of the readout of the location of the tool holder may be compromised.